Fecal α₁-proteinase inhibitor concentration in dogs with chronic gastrointestinal disease

Background: Fecal α₁-proteinase inhibitor (α₁-PI) clearance is a reliable, noninvasive marker for protein-losing enteropathy in human beings. An assay for use in dogs has been developed and validated. Objective: The aim of this study was to evaluate fecal α₁-PI concentration in dogs with chronic gastrointestinal disease, compared with healthy dogs, and to assess its correlation with serum albumin concentration. Methods: Fecal samples were collected from 2 groups of dogs. Group 1 consisted of 21 clinically healthy client-owned dogs without signs of gastrointestinal disease. Group 2 consisted of 16 dogs referred for investigation of suspected gastrointestinal disease. On the basis of gastric and duodenal biopsies, group 2 was further subdivided into dogs with normal histology (n = 9) and those with histologic abnormalities (n = 7: inflammatory bowel disease, n = 3; lymphangiectasia, n = 4). An ELISA was used to measure α₁-PI concentrations in fecal extracts. Results: Fecal α₁-PI concentrations, expressed as μg/g of feces, were not significantly different between groups 1 and 2 as a whole. However, fecal α₁-PI concentrations (median, minimum-maximum) were significantly higher in dogs with gastrointestinal diseases associated with histologic abnormalities (60.6 μg/g, 7.4-201.7 μg/g) compared with dogs with normal histology (3.8 μg/g, 0.7-74.0 μg/g) and control dogs (9.9 μg/g, 0.0-32.1 μg/g). There was no significant correlation between fecal α₁-PI and serum albumin concentrations in dogs with gastrointestinal disease. Conclusions: Increased fecal α₁-PI concentration may signal the need to obtain gastrointestinal biopsies for a final diagnosis. Fecal α₁-PI concentration may be a useful test for early detection of protein-losing enteropathy before decreases in serum albumin concentration can be detected.